Previously known vibrating tampers are equipped with a number of different operating controls, such as a fuel valve, a closable fuel tank venting valve, a throttle control and a switch for stopping the engine. These controls are usually mounted in different positions on the tool and are not always easily accessible. Ease of access is a prerequisite to the safe operation of the vibrating tamper both when using the tool and during transport.
It is an object of the invention to simplify and make safer the use of vibrating tampers powered by internal combustion engines and designed for compacting clay, sand or gravel, for example in pipe trenches.
To achieve simple and safe operation of a vibrating tamper, the tool is, in accordance with the invention, equipped with a single control lever with three distinct snap-action positions with the following functions:
position 1: engine off, fuel valve closed and fuel tank venting valve closed;
position 2: throttle control in starting/idling position, fuel tank venting valve open and fuel valve open; and,
position 3: throttle control in full-throttle position, fuel tank venting valve open and fuel valve open.
The different control lever settings are made distinct by means of a snap-action device which fixes the lever securely in the required position. This is important since the setting of an intermediate position during operation may, for example, damage the centrifugal clutch between the engine and the actual tamping mechanism. Ensuring that the fuel valve is closed when transporting the compactor is important since the tool will often be carried in a random manner. Otherwise, if the fuel valve is open, fuel may run into the engine oil, leading to subsequent engine failure, or leak out through the carburetor.
For safety reasons, it is essential for the fuel tank venting valve to be closed when transporting the tool to prevent fuel leakage through the venting valve. In the event of an emergency when using the tamper, the engine can be stopped easily by moving the control lever to position 1, in which the fuel supply and fuel tank venting valves are closed automatically.